This invention relates generally to gas turbines and more particularly to fuel control systems used with gas turbines.
At least some known industrial gas turbine fuel control systems rely upon a steady fuel pressure, know as a P2 pressure, upstream of a set of parallel gas control valves for proper operation. To facilitate controlling the fuel pressure, at least some known gas turbine engines include a pressure control valve immediately upstream from the set of parallel gas control valves.
However, at least some engines using such fuel control systems still experience oscillating fuel pressures (P1) upstream from the parallel gas control valves. For example, a P2 oscillation induced by P1 supply pressure may result in a poor tracking action of the control system with the controlled parameter. In addition, such pressure oscillations may also be caused by variations in the gas fuel supply pressure, known as P1 pressure. Known control systems generally act solely on the P2 error, but have poor P1 disturbance rejection capability.